Myocardial Infarction In Adult Rats Research Articles

Morroniside induces cardiomyocyte cell cycle activity and promotes cardiac repair after myocardial infarction in adult rats.

Introduction: Acute myocardial infarction (AMI) is characterized by the loss of cardiomyocytes, which impairs cardiac function and eventually leads to heart failure. The induction of cardiomyocyte cell cycle activity provides a new treatment strategy for the repair of heart damage. Our previous study demonstrated that morroniside exerts cardioprotective effects. This study investigated the effects and underlying mechanisms of action of morroniside on cardiomyocyte cell cycle activity and cardiac repair following AMI. Methods: Neonatal rat cardiomyocytes (NRCMs) were isolated and exposed to oxygen-glucose deprivation (OGD) in vitro. A rat model of AMI was established by ligation of the left anterior descending coronary artery (LAD) in vivo. Immunofluorescence staining was performed to detect newly generated cardiomyocytes. Western blotting was performed to assess the expression of cell cycle-related proteins. Electrocardiography (ECG) was used to examine pathological Q waves. Masson's trichrome and wheat germ agglutinin (WGA) staining assessed myocardial fibrosis and hypertrophy. Results: The results showed that morroniside induced cardiomyocyte cell cycle activity and increased the levels of cell cycle proteins, including cyclin D1, CDK4, cyclin A2, and cyclin B1, both in vitro and in vivo. Moreover, morroniside reduced myocardial fibrosis and remodeling. Discussion: In conclusion, our study demonstrated that morroniside stimulates cardiomyocyte cell cycle activity and cardiac repair in adult rats, and that these effects may be related to the upregulation of cell cycle proteins.

Sirtuin3 protects aged human mesenchymal stem cells against oxidative stress and enhances efficacy of cell therapy for ischaemic heart diseases.

Sirtuin3 (SIRT3) is associated with oxidative stress and lifespan. However, the possible mechanisms underlying its influence are unknown. We hypothesized that SIRT3 increases the antioxidant capacity of aged cells and improves the efficacy of human mesenchymal stem cell (hMSC) therapy for ischaemic heart diseases in aged patients. In vitro, the antioxidant capacity of old hMSCs (O‐hMSCs) was increased after SIRT3 overexpression using a gene transfection technique, while the antioxidant capacity of young hMSCs (Y‐hMSCs) was decreased by SIRT3 silencing. The levels of forkhead box O3a (FoxO3a) in the nucleus, and antioxidant enzymes Mn‐superoxide dismutase (MnSOD) and catalase (CAT) increased in SIRT3‐overexpressed O‐hMSCs while they decreased in SIRT3‐silenced Y‐hMSCs after oxidative stress. Following myocardial infarction in adult rats in vivo, infarct size decreased and cardiac function was significantly enhanced after cell transplantation with SIRT3 overexpressed O‐hMSCs. The number of apoptotic cells decreased and the survival rate of transplanted cells increased following SIRT3 overexpression in O‐hMSCs. SIRT3 protects aged hMSCs against oxidative stress by positively regulating antioxidant enzymes (MnSOD and CAT) via increasing the expression of FoxO3a in the nucleus. The efficacy of aged hMSC transplantation therapy for ischaemic heart diseases can be improved by SIRT3 overexpression.

Abstract 11983: Auraptene, a Coumaric Compounds Analogous, Improved the Worsening of Systolic Function by Activating Mitochondrial Function After Myocardial Infarction in Rats

Introduction: Heart failure is associated with pathological growth and mitochondrial dysfunction of constituent cardiomyocytes. To achieve effective oral pharmacological therapy for heart failure, we screened compounds isolated from natural products and found that auraptene derived from the peel of Citrus Hassaku may be applicable to pharmacological therapy for heart failure. Hypothesis: We assessed the hypothesis that auraptene could improve the deterioration of mitochondrial function and the development of heart failure in rats with myocardial infarction (MI). Methods and Results: In cultured cardiomyocytes, auraptene (2.5-10 μM) dose-dependently repressed phenylephrine-induced hypertrophic responses such as increase in cell size and ANF and ET-1 promoter activations. Auraptene also activated mitochondrial- and lipid metabolism-related gene transcriptions, such as PGC1α, PPARα/γ, mCPT1, UCP3, and PDK4. One week after operation, 22 rats with a moderate size of MI (Fractional shortening (FS) < 40%) were then randomly assigned to vehicle (n=8), auraptene low-dose (5 mg/kg/day, n=7), or high-dose (50 mg/kg/day, n=7). Oral daily treatments with these agents were continued for 6 weeks. There were no differences in left ventricle (LV) geometric and functional data among the 3 MI groups before treatment. After treatment, LVFS was significantly higher in the auraptene low-dose (21%, p < 0.0001) and high-dose (26%, p < 0.0001) groups than the vehicle group (16%). LV wall thickness in the remote non-infarct area was significantly thinner in the auraptene low-dose (1.4 mm, p < 0.01) and high-dose (1.2 mm, p < 0.0001) groups than the vehicle group (2.5 mm). Histological analysis demonstrated that auraptene treatment significantly suppressed MI-induced increases in myocardial cell diameter and perivascular fibrosis compared with vehicle treatment. Moreover, auraptene also prevented the activations of ANF and MCP-1 mRNA levels and up-regulated mitochondrial- and lipid metabolism-related gene transcriptions in LV. Conclusions: Auraptene treatment prevents the worsening of LV systolic function and represses hypertrophy after MI in adult rats. A natural compound, auraptene is expected as a novel useful agent for heart failure therapy in humans.